1. Field of this Invention
This invention relates to a process for the production of 3-picoline.
2. Prior Art
Pyridine bases represent important intermediate products in the chemical industry, for example, in the case of the production of nicotinic acid or nicotinic acid amide. Various processes are known for the production of pyridine bases.
Nowadays, 2-methyl-5-ethylpyridine is produced on a large scale in the liquid phase process from acetaldehyde or paraldehyde and ammonia in the presence of very diverse types of catalysts, such as, ammonium salts. Small quantities of 2- and 4-picoline are obtained as by-products.
2- and 4-picoline are produced in gas phase reactions at a temperature of about 400.degree. C. from acetaldehyde and ammonia with the use of solid bed or moving bed catalysts on the basis of aluminum silicate.
For the production of pyridine as well as of 3-picoline, which achieves ever greater importance, gas phase reactions are currently used whereby through the addition of formaldehyde to the acetaldehyde, the formation of 2- and 4-picoline is suppressed in favor of 3-picoline. These reactions also take place in a solid bed or moving bed with aluminum silicate as a catalyst at a temperature of about 400.degree. C. According to these processes, yields of 3-picoline in the order of magnitude of at most 40 to 44 percent is achieved. Beside that, large quantities of pyridine are obtained.
It is further known that one may start out, instead of from saturated aldehydes, from unsaturated aldehydes, such as, acrolein or croton-aldehyde. These reactions take place in the gaseous phase at high temperatures; the yields are essentially as high as in the case of the use of saturated aldehydes as starting material.